I am currently using a gravity watering system but it freezes very easily once it leaves my container and goes into the tubing.
Edited by KeithKZ - 4/10/16 at 9:54am
Unfortunately this will only help a tiny bit. The freezing point of vinegar is 28 degrees Fahrenheit. And that is pure. Diluting it in water will most likely bring you back to within a fraction of a degree of the "normal" water freezing temperature.
I think the major issue with the gravity feed shown is that the tubes are so small in diameter, and they are so exposed. I think the only good solution with the current system is to insulate the lines, or to somehow heat the water. But even heating would not help much since the water in the lines will cool quickly. Movement would help, but there is no good way to do that since this system gravity feeds into bowls.